The present invention relates to certain hydrocarbon soluble or dispersible amide reaction products (referred to herein as Component-1), and mixtures, and/or acid amine salts of Component-1 and certain acid/esters (said acid/esters being referred to herein as Component-2), which are useful as friction modifying additives for oleaginous compositions such as lubricating oils, including power transmitting fluids, particularly automatic transmission fluids (ATF), and to the oleaginous compositions in which they are contained.
There are many instances, as is well known, particularly under boundary lubrication conditions where two moving surfaces in contact with each other must be lubricated, or otherwise protected, so as to prevent wear, and to insure continued movement. There are other instances where friction between two rubbing surfaces is sought to be modified but not necessarily minimized. By controlling friction between two surfaces, the energy transferred from one surface to another is also controlled.
For example, specialized properties sought to be imparted to certain lubricating oil compositions adapted for use as an automatic transmission fluid are the friction characteristics of the fluid. These properties distinguish automatic transmission fluids (ATF) from other lubricants, and in fact between types of ATF's as well. Such characteristic qualities have received the most attention by both the transmission manufacturers and fluid producers for many years. This attention stems from the fact that the friction requirements of an ATF are unique and depend on the transmission and clutch design, as well as on the type of clutch plate material used.
As is also well known, frictional characteristics of lubricants can be controlled through the addition of suitable additives with varying degrees of success.
While there are many known additives which may be classified as friction modifying agents, it is also known that many of these additives act in a different physical or chemical manner and often compete with other additives, such as anti-wear additives for the surface of the moving metal parts which are subjected to lubrication. Accordingly, extreme care must be exercised in the selection of these additives to insure compatibility and effectiveness.
Various tests have been designed by transmission manufacturers for measuring ATF friction. The object of these tests is to evaluate the performance of ATF additives against the requirements of particular transmission design and their ability to impart transmission durability and smooth shifting under a variety of road conditions.
One way to evaluate friction modification under simulated transmission operating conditions is in an SAE No. 2 friction apparatus. In this test, a test head containing a test clutch pack and the fluid is fitted to an electric motor with an inertia disc. The motor and flywheel of the friction machine (filled with fluid to be tested) are accelerated to constant speed, the motor is shut off and the flywheel speed is decreased to zero by application of the clutch. The clutch plates are then released, the system is again accelerated to constant speed, and the clutch pack which is immersed in the test fluid is engaged again. This process is repeated many times with each clutch engagement being called a cycle. The number of cycles employed for a given test is determined by the particular test being run.
During the clutch application, friction torque is recorded as a function of time. The friction data obtained are either the torque traces themselves or friction coefficients calculated from the torque traces. The shape of the torque trace desired is set by the transmission manufacturer. One way of characterizing friction performance is to determine the torque: (a) when the flywheel speed is midway between the maximum constant speed selected and zero speed (such torque measurement is referred to herein as T.sub.D) and (b) when as the flywheel speed approaches zero rpm (such torque measurement is referred to herein as T.sub.O). Such torques can then be used to determine the torque ratio which is expressed as T.sub.O /T.sub.D, or alternatively, to determine the torque differential T.sub.O -T.sub.D. The optimum target values for torque ratio and torque differential are set by the auto manufacturers and can be different for each manufacturer. As the T.sub.O /T.sub.D increasingly exceeds 1.0, a transmission will typically exhibit shorter harsher shifts as it changes gears. On the other hand as T.sub.O /T.sub.D decreases below 1.0, there is an increasingly greater danger of clutch slippage when the transmission changes gears. Similar relationships exist with respect to a T.sub.O -T.sub.D target value of 0.
If the torque traces are converted to friction coefficients, the torque ratio can be expressed as .mu..sub.O /.mu..sub.D, where .mu..sub.O is the friction coefficient of T.sub.O and .mu..sub.D is the friction coefficient of T.sub.D.
In addition to constraints placed on the torque ratio, many transmission manufacturers require that the dynamic torque T.sub.D be at least a certain minimum value. This stems from the fact that high dynamic friction produces short efficient lock-ups. This, in turn, minimizes absorption of energy by the fluid and clutch thereby also minimizing fluid temperature.
While many automatic transmission fluids can achieve acceptable torque ratios and meet minimum dynamic torque targets after a minimum number of cycles, it becomes increasingly more difficult to sustain such target values as the number of cycles are increased. The ability of an ATF to sustain such desired friction properties over time is referred to herein as friction stability or durability.
Attempts to improve friction stability by simply adding more friction modifier have not met with success because this tends to reduce overall fluid friction properties, and particularly the breakaway static torque (T.sub.S) of the fluid. This parameter, or alternatively, the breakaway static torque ratio (T.sub.S /T.sub.D) reflect the relative tendency of engaged parts, such as clutch packs, bands and drums, to slip under load. If this value is too low, the slippage can impair the driveability and safety of the vehicle.
More specifically, breakaway static torque (T.sub.S) is determined upon completion of certain predetermined cycles of the dynamic torque evaluation sequence. In the T.sub.S determination after the flywheel has returned to 0 rpm, it is again accelerated to a lower rpm, e.g., 1 rpm without the clutch engaged. At 1 rpm, the clutch is engaged, but not released, and hence does not turn. Upon clutch engagement, the torque applied by the flywheel is measured as a function of time for a brief period as slippage of the flywheel occurs.
Another aspect of friction modification is observed in clutches at low relative sliding clutch speeds. The operation whereby a clutch pack fully engages is often referred to as lock-up. Continuing operation of the clutch at low sliding speeds, or partially locked-up, can cause the clutch plates to grab and release intermittently. This phenomena is referred to as stick-slip and is experienced by the driver as a shudder in the automobile.
A still further aspect of friction modification is the break-in period. Typically, when testing an ATF, one can observe a change in frictional performance with time. This change occurs over a duration often referred to as the break-in period. It is an advantage to employ a friction modifier which does not exhibit a break-in period or which yields a very short break-in period.
Transmission designs have undergone radical changes, thereby necessitating the formulation of ATF additives capable of meeting new and more stringent requirements needed to match such design changes.
No base oil alone can even approach the many special properties required for ATF service. Consequently, it is necessary to employ several chemical additives, each of which is designed to impart or improve a specific property of the fluid. Consequently, it becomes particularly advantageous when one additive can perform more than one function, thereby reducing the number of additives needed to be present in the formulation.
Accordingly, there has been a continuing search for new additives possessed of one or more properties which render them suitable for use in ATF compositions, as well as other oleaginous compositions. There also has been a search for new combinations of additives which not only provide ATF compositions, as well as other oleaginous compositions, with the various specific properties that are required, but which are compatible with each other in the sense that they do not exhibit any substantial tendency to compete with each other, nor to otherwise reduce the effectiveness of the various additives in the compositions. The present invention was developed in response to this search.
U.S. Pat. No. 4,702,850 discloses certain C.sub.12 -C.sub.50 hydrocarbyl substituted succinate esters of thiobisethanol as friction modifiers in automatic transmission fluids. These additives are included in the scope of the succinate ester Component-2 reactant employed in the present invention.
U.S. Pat. No. 4,664,826 discloses certain metal (e.g., Ca and Mg) ester salts of the above described succinate esters as friction modifiers in an ATF.
U.S. Pat. No. 4,760,170 discloses a solution process for preparing certain oil solubilized metal ester salts of the type described above.
U.S. Pat. No. 4,776,969 discloses certain cyclic phosphate anti-wear additives which may be employed with the above described succinate ester friction modifiers. At Col. 14, lines 60 et seq., additional friction modifiers are disclosed.
U.S. Pat. No. 3,634,256 discloses an automatic transmission fluid containing (1) a friction modifier selected from the group consisting of oxyalkylated aliphatic tertiary amines, 1-hydroxyalkyl-2 alkyl imidazolines (e.g.,
1-hydroxyethyl-2-heptacecyl-2-imidazoline) and mixtures thereof, and (2) an oil soluble polyalkenyl substituted succinimide of an alkylene polyamine. Note further Col. 2, Line 49 et seq., wherein further imidazoles are disclosed.
U.S. Pat. No. 2,622,067 discloses the amide containing reaction product of long chain aliphatic monocarboxylic acid and polyalkylene polyamines as an emulsifying agent for stabilizing water-in-oil emulsions.
U.S. Pat. Nos. 2,693,468 and 2,713,583 disclose imidazoline containing materials for use in lubricants.
U.S. Pat. No. 2,736,658 discloses the use of polyamine fatty acid salts and corrosion inhibitors for lube oils.
U.S. Pat. No. 3,857,791 discloses a 2-component mixture comprising a high molecular weight amido-amine acid and high molecular weight hydrocarbyl amine, particularly for 2-cycle engine oils.
U.S. Pat. No. 2,291,396 discloses a class of wax modifiers which are prepared by condensing polyalkylene polyamines with fatty acids, preferably fatty acids having more than 10 carbon atoms. The wax modifiers are disclosed as being useful as a pour depressant for waxy mineral oils when used in amounts of from about 0.1 to about 10%, preferably from 0.5 to 5%. The modifiers are also disclosed as being suitable for use as a dewaxing aid, or as an addition agent to paraffin wax, or other normally hard, brittle wax, to modify the properties thereof.
U.S. Pat. No. 3,000,916 relates to rust inhibiting additives for engine lubricating oils which are prepared by first reacting polymerized linoleic acid with an amine, and then reacting the acid-amine condensate with boric acid. See also U.S. Pat. No. 2,568,876.
U.S. Pat. No. 3,251,853 relates to oil-soluble nitrogen-containing compositions which are useful as additives for lubricating compositions for internal combustion engines, such as two-cycle spark ignition engines which utilize an oil-fuel mixture as a lubricant. The nitrogen-containing compositions are prepared by reacting an amine and a branched chain acid having from about 14 to 20 aliphatic carbon atoms in the principal chain and at least one aliphatically substituted pendant aryl group. A similar disclosure is set forth in U.S. Pat. No. 3,405,064, except that the branched chain acid has a pendant lower acyclic aliphatic group instead of a pendant aryl group, and the nitrogen-containing product is characterized by the presence of amidino linkages.
U.S. Pat. No. 3,110,673 relates to an ashless detergent lubricant composition having pour point depressing properties. The composition contains about 0.1 to 10% of a pour point lowering and dispersing agent additive comprising a polyamide formed by reacting a polyalkylene polyamine with a blend of straight chain fatty acids and branched chain fatty acids. The polyamides are such that they contain from 1 to 3 amine groups in addition to amide groups. See also, U.S. Pat. Nos. 2,852,467, 3,169,980 and 2,435,631.
U.S. Pat. No. 4,634,543 relates to a fluid composition for use in a shock absorber. The fluid composition comprises a lubricating oil, a boron-containing compound and a phosphorus-containing compound such as a phosphate, phosphite or the like. The boron-containing compound may be prepared, for example, by reacting the reaction product of isostearic acid and tetraethylene pentamine with boric acid.
U.S. Pat. No. 4,705,643 discloses an ashless two-stroke cycle additive which is prepared by condensing a fatty acid such as isostearic acid and a polyamine having at least three amine groups such as tetraethylene pentamine. The additive is said to maintain engine cleanliness and is used at a concentration level of about 10% in combination with a lubricating oil. See also, U.S. Pat. No. 2,622,018 for the use of such materials as gasoline additives.
U.S. Pat. No. 2,750,342 discloses a class of synthetic phosphorous- and sulfur-containing compounds which are useful as lubricating oil additives and which are characterized by the general formula: ##STR1## in which R represents a saturated aliphatic C.sub.2 -C.sub.3 hydrocarbon group, X.sub.1, X.sub.2 and X.sub.3 each represent O or S, and R.sub.1,R.sub.2 and R.sub.3 each represent a C.sub.1 -C.sub.18 alkyl group or a series of saturated aliphatic hydrocarbon groups interlinked by O or S atoms.
U.S. Pat. No. 2,960,523 discloses phosphoric ester derivatives of hydroxyalkyl vinyl sulfides having the general formula: ##STR2## where A is a C.sub.2 -C.sub.6 alkylene group, and R.sub.1 and R.sub.2 each are C.sub.1 -C.sub.4 alkyl groups. The disclosed ester derivatives can be copolymerizable with various acrylic esters to provide copolymers which have utility as flame-proofing agents for textiles and paper products.
U.S. Pat. No. 3,446,738 discloses an ester base lubricating composition comprising an aromatic amine and an organic thiophosphite or thiophosphonate having the formula: ##STR3## wherein X is O or S, at least one X being S; n is 0 or 1, but at least three n's being 1; and R.sub.1,R.sub.2 and R.sub.3 are alkyl or aromatic groups. The organic thiophosphite or thiophosphonate functions as an anti-oxidant.
U.S. Pat. No. 4,081,387 discloses lubricating compositions comprising a major proportion of lubricating oil and a minor proportion of at least one phosphorous- and sulfur-containing additive of the formula: EQU Y.sup.a --S--Y.sup.b
wherein Y.sup.a is ##STR4## and wherein Z is a saturated or unsaturated hydrocarbyl group; each R.sub.1 and R.sub.2 , independently, is a hydrocarbyl, hydrocarbyloxy or hydrocarbylmercapto group having from 1 to 10 carbon atoms; R.sub.3 is hydrogen or a C.sub.1 -C.sub.30 hydrocarbyl group; X is S or O; and Y.sup.b is --R.sub.4 H or --R.sub.4 --S--R.sub.5, wherein R.sub.4 is a C.sub.1 -C.sub.30 divalent hydrocarbyl group and R.sub.5 is H or Y.sup.a. The disclosed lubricating compositions exhibit increased resistance to oxidative degradation and anti-wear properties.
U.S. Pat. No. 4,511,480 discloses phosphite esters of oxyalkylated thiols as corrosion inhibitors for ferrous metals in deep gas wells. The disclosed esters have the formula: ##STR5## where R.sub.1 represents alkyl, cycloalkyl, aryl, aralkyl and heterocyclic; R.sub.2 represents alkyl; x is 1-4, m is 1 or 2; n is 1 when m is 2 and n is 2 when m is 1.
U.S. Pat No. 3,933,659 discloses lubricating oil composition which comprise a major amount of an oil of lubricating viscosity, and an effective amount of each of the following: (1) an alkenyl succinimide, (2) a Group II metal salt of a dihydrocarbyl dithiophosphoric acid, (3) a compound selected from the group consisting of (a) fatty acid esters of dihydric and other polyhydric alcohols, and oil soluble oxyalkylated derivatives thereof, (b) fatty acid amides of low molecular weight amino acids, (c) N-fatty alkyl-N,N diethanol amines, (d) N-fatty alkyl-N,N-di- (ethoxyethanol) amines, (e) N-fatty alkyl-N,N-di-poly- (ethoxy) ethanol amines, and (f) mixtures thereof, and (4) a basic sulfurized alkaline earth metal alkyl phenate. Such lubricating compositions are useful as functional fluids in systems requiring fluid coupling, hydraulic fluid and/or lubrication of relatively moving parts, particularly as automatic transmission fluids.
U.S. Pat. No. 4,201,684 relates to lubricating oil compositions adapted for use as a crankcase lubricant in internal combustion engines containing a friction reducing amount of a sulfurized fatty acid amide, ester or ester-amide of an oxyalkylated amine.